In digital cellular systems today, for example in the Global System for Mobile communications (GSM) system, mobile stations monitor and measure various signals from a serving network. For example, when a GSM mobile station is initially turned on and enters the idle mode, the mobile station initiates finding a strongest Broadcast Control channel (BCCH) carrier based on the frequencies stored in its Subscriber Information Module (SIM) card. Once the idle mobile station becomes active, also known as entering dedicated mode, and a call is set up to or from the mobile station, the mobile station receives an active BCCH Allocation list (BA-list) on a Slow Associated Control Channel (SACCH) message. Frequencies associated with cells are identified in the active BA-list. The mobile station should periodically measure signal strength of the frequencies in the BA-list. Results from those measurements are reported to the network in periodic measurement reports. The network may use received measurement reports when generating a hand-off candidate list, and the like.
Generally, SACCH messages are broadcast by one or more base stations. These SACCH messages are broadcast to mobile stations on traffic channels. When a mobile station receives a SACCH message, the content thereof may be in the form of a bit map identifying particular BCCH channel frequencies of neighboring cells. The mobile station is tasked with making signal quality measurements on the BCCH channel frequencies, and reporting those measurements to a serving base station. The measurements are incorporated in a measurement report.
Conventionally, the BCCH channel frequencies contained in the SACCH message replace any and all BCCH channel frequencies currently stored in a memory of the mobile station. Moreover, any measurement reports associated with the currently stored BCCH frequencies are deleted when a new or updated list of BCCH channels is received. In particular, conventional mobile stations are not intelligently enabled to discern whether one or more of the received BCCH channel frequencies match one or more of the BCCH channel frequencies currently stored the memory of the mobile station.